WASHINGTON (AFP) -- President Donald Trump suffered a bitter defeat Friday in his first major legislative challenge as Republican lawmakers shot down his effort to repeal Obamacare. It was the latest in a string of major setbacks to have hit his two-month-old presidency.

Travel bans

Just one week after his inauguration, Trump issued an executive order banning travelers from seven majority-Muslim countries and all refugees.

Unveiled with no prior warning, it sowed travel chaos and confusion, and ignited worldwide outrage.

However, in a humiliating setback for the president, a court in Washington state blocked the order on the grounds that it violated the constitution's prohibition of religious discrimination.

After the block was upheld on appeal, the administration issued a revised ban it said would better adhere to the law. It would close US borders to nationals of Iran, Libya, Somalia, Sudan, Syria and Yemen for 90 days, and all refugees for at least 120 days. Iraq was on the original ban but removed in the revision.

Still, courts in Maryland Hawaii dealt the White House a new blow this month, ruling that the second ban also discriminated against Muslims.

Although it does not mention Muslims, the courts have accepted arguments that Trump's statements while he was running for president last year -- that he would open his White House term with a ban on Muslim arrivals -- effectively defined his approach.

The case will next be heard in a federal appeals court in Richmond, Virginia.

Russia

Since US intelligence agencies last year took the unprecedented step of publicly accusing Russia of trying to swing November's presidential election in Trump's favor, questions have swirled about whether some in his campaign colluded with Moscow.

At least four separate congressional investigations are underway into Moscow's election meddling. Democrats argue that the interference, in which the Kremlin oversaw a campaign to hack Democratic Party emails that were later leaked, contributed to Hillary Clinton's defeat.

The cloud hanging over the White House mushroomed last month when Trump's national security adviser Michael Flynn resigned after it emerged that he had misled the White House over meeting Russia's Ambassador in Washington Sergey Kislyak before taking office.

Attorney General Jeff Sessions recused himself from any Russia-related inquiries soon after, following the revelation that he also met Kislyak before Trump took office, contrary to Sessions's testimony during his confirmation hearing.

In a high-stakes public hearing in Congress on Monday, FBI Director James Comey took the extraordinary step of confirming the agency is investigating whether Trump campaign aides colluded with the Russian effort to influence the election. He also repudiated the president's claim that he was wiretapped by Barack Obama.

Both the House and Senate Intelligence Committees will hold more public hearings in the coming weeks.

Health care

On Friday, Trump was forced to withdraw an embattled Republican health care bill moments before a vote, leaving his major campaign pledge to dismantle his predecessor's health care reforms unfulfilled.

The plan, intended to bring free-market competition to the insurance industry and lower the cost of premiums for most Americans, would have slashed public assistance to people with no health coverage through their employers.

Some 14 million people stood to lose their coverage starting next year, forecasts said.

Trump had thrown his full political weight behind the measure, spending days arm-twisting recalcitrant Republicans.

The billionaire real estate tycoon -- who entered the White House with no experience of politics or government -- had put his reputation as a dealmaker on the line with the high-risk vote.

But the bill now appears dead, with Republican lawmakers urging a return to the drawing board.

Trump said he would shift quickly toward tax reform, another longstanding Republican goal.